Question

The quantitation of proteins due to their absorbance at 280 nm (uv region) is due to the large absorbtivity of the ________ amino acids?

1) Polar
2) Nonpolar
3) Aromatic
4) Basic

Answer 1

Protein quantitation at 280 nm is due to the high absorbance of aromatic amino acids like tryptophan, phenylalanine, and tyrosine, which are responsible for protein fluorescence.

Step-by-step explanation:

The quantitation of proteins due to their absorbance at 280 nm in the UV region is primarily attributed to the large absorbance of the aromatic amino acids. These amino acids, specifically tryptophan, phenylalanine, and tyrosine, are responsible for the absorption because they contain conjugated pi systems that can undergo transitions allowing them to strongly absorb light in the UV range. The presence of these aromatics is what contributes to the characteristic fluorescence exhibited by proteins when they re-emit light at different wavelengths after being excited.